The mine exploded on schedule at 7:20 a.m., 100 years ago, July 1, 1916. British sappers had tunneled for months under the no man's land separating the Allied British-French trenches from those of the Germans, and placed 40,000 pounds of high explosive under the German redoubt on Hawthorn Ridge. A British cameraman filmed the explosion, which can be viewed today on the internet.

Like so much else that day, what then unfolded followed months of meticulous planning, with disastrous results.

The Allies chose the Somme River region of France for their 1916 offensive on the Western Front mainly because that was where the British and French trench lines met. But while intended from the beginning as a joint effort, by the time it was launched the offensive had become predominantly a British one. The Germans had upset plans by their earlier unleashing of a fierce offensive against the French at Verdun.

So on July 1 the first waves of 120,000 infantrymen from Britain and her dominions climbed out of their trenches and walked closely abreast in long lines toward the German trenches. They "walked" because generals and infantry alike were certain that the seven-day artillery bombardment preceding the infantry attack had left no German soldiers still alive in their first-line trenches. They were wrong.

The Hawthorn mine killed and injured hundreds of Germans — and alerted all the others along the 18-mile Somme front that the long-expected infantry attack was imminent. The preliminary bombardment had not destroyed the German dugouts, some 60 feet deep, or their inhabitants. By the time the British infantry left their trenches, German troops had already reached the parapets of theirs, with machine guns hauled up and readied for action.

The no man's land the infantry had to cross ranged from 200 to 1,500 yards across. The Germans' Maxim machine guns, firing 500 bullets a minute, were deadly accurate up to more than 2,000 yards. German artillery now also crashed down on the exposed infantry. Meanwhile, according to plan, the British had lifted their artillery fire off the first-line German trenches.

On that first day, few of the infantry reached a German trench. The British-led forces suffered more than 57,000 casualties, with nearly 20,000 deaths. Some isolated objectives were achieved, but most were lost following German counterattacks.

Despite all, however, the Somme battle slogged on until Nov. 18. No general breakthrough was attained, and the territory gained by the end amounted to a few square miles.

The final "butcher's bill" on both sides: More than 1 million casualties.

Years after the war, it became fashionable to describe the British infantry as "lions led by donkeys" — brave men conveyed to slaughter by stupid, soulless generals plotting safely behind the lines in sumptuous chateaus.

The Somme, especially the first day, was a human catastrophe. But to remember the fighting there only for its cascade of failures and horrors is ahistorical. Generals on both sides had been struggling since late 1914, when trench warfare set in, to discover how to defeat armies dug in behind modern fortifications. After much trial, error and killing, the British at the Somme learned from their mistakes and adapted tactics that would bring victory to the Allies in 1918.

It was not a perfect learning curve. Passchendaele in Flanders followed in 1917, with some of the same mistakes reprised. But tanks, introduced to warfare by the British at the Somme, albeit in primitive form and inconsequential numbers, were used effectively by 1917, decisively in 1918. After the Somme, pre-attack artillery bombardments were shortened or eliminated to enhance surprise. British artillerymen also became expert at the devastating "creeping barrage," which kept just ahead of the attacking infantry, who no longer advanced slowly at close intervals in orderly company lines, but stealthily in smaller, dispersed platoons.

It was no mere coincidence that the German army went over to the defensive at Verdun within two weeks of the start of the Somme campaign, or that less than three months after it concluded, a desperate Germany resumed unrestricted submarine warfare, which soon brought the United States into the war.

Some historians have concluded that given the constraints of the times, carnage at the Somme was inevitable. But with its far-ranging consequences, and despite all the folly, it is plausible that the offensive was as important to the winning of the First World War as the D-Day assault was to the winning of the Second.

For that, the fallen of the Somme deserve to be remembered not as guileless victims or the inspiration for war poetry, but for what they were: Heroes.

Kirk O. Kolbo is a Minneapolis attorney.